Pneumatics and FIRST FIRST Training 2015.pdu

Power Transmission & Control  Electrical  Mechanical  Fluid Power  Hydraulics - not allowed on FIRST robots  Oil, Water, other liquids  Pneumatics  Air, other gases

Pneumatics  Compressor  Connectors  Valves  Directional control  Flow control  Pressure control Converts Electrical Energy – to Pressurized Volume of Air Analogous to Wires & Terminals Analogous to Relays & Controllers

Pneumatics that may be included in the FIRST kit  Compressor and related components  Connectors and tubing  Valve(s)  Actuator (may need to order – check the kit of parts)

Pneumatics - Advantages  Weight equal or lighter than comparable alternatives  Simple  Adjustable Force  Different bore cylinders change the available force and  By adjusting the applied pressure you can instantly adjust the force FIRST Training 2015.pdu

Pneumatics – Advantages  Durable no burned up motors – stall with no damage  Strong from 9 lbs to 180 lbs – easily adjustable  Custom cylinders in just a few days by UPS  Last minute additions add a valve or a cylinder quickly FIRST Training 2015.pdu

Pneumatics  Actuators  Linear – Often called cylinders – can be made to perform complex motions by using mechanical components  Rotary  Limited Rotation  Self-contained  Rack and pinion or lever  Clamps FIRST Kickoff jrg

1. Forces from 9 to 180 lbs. can be easily achieved 2. Custom actuators are available quickly 3. Easy to add extra functionality 4. Simple to apply

FIRST Components Overview FIRST Kickoff jrg

Compressor  Electrically Driven  Additional Components Relief Valve on Compressor Limits the maximum system pressure Pressure Switch Signals the controller to start or stop the compressor Tank Stores energy Plug Valve Stops air flow Gauge Reads available pressure

The Compressor System  Electrically driven Check Valve Flow in one direction built into compressor Compressor and Relief Valve Tanks and Pressure Switch Gauge and Plug Valve Regulators with gauges

The Compressor System Additional Components FIRST Kickoff jrg Tanks & Gauge Pressure Switch Relief Valve Plug Valve Pressure In NCNO Common

Air Supply - Regulator  Regulators Control Pressure  Relieving type in the FIRST kit – 2 are included  Non-Relieving type can trap pressure Set Regulators to about twice minimum pressure necessary to operate the cylinder under load Relieving Regulator and gauge symbol

 Compressed air is a form of stored energy  like a spring, a battery, a weight  Maximum pressure from the compressor is a function of bore, stroke and motor horsepower  The ratio of the uncompressed volume to the compressed volume is the compression ratio  Relief Valve setting determines the “maximum system pressure”  Compressed Air is stored in one or more tanks  The higher the storage pressure, the more usable energy will be available FIRST Kickoff jrg SAFETY FIRST

Connectors  Hundreds of Variations Available  Size, Type of Connection, Number of Ports  Tubing or Pipe – wrap teflon® tape correctly Tapered Pipe Thread Generally Brass Use Teflon Tape Correctly

Fittings Connection and Disconnection

Some Facts about Pneumatics  Pressure – Potential Energy  Lbs per in 2 or Force per unit area  Absolute Pressure – 14.7 psia at sea level  Gauge Pressure – measured relative to ambient  Flow  cfm or Volume per unit time  Scfm Voltage Current

More Facts about Pneumatics  Universal Gas Laws – Boyle’s Law if Temperature remains constant  P 1 x V 1 = P 2 x V 2 if Temperature remains constant absolute pressure  That means if you cut the volume in half the absolute pressure doubles – That’s how the Compressor works Relationship between Bars, Gauge and Absolute Pressure Bars Gauge Bars Absolute PSIG Gauge PSIA Absolute

Force Principles Gauge Pressure works against each square inch of piston surface The greater the square inch surface of the fluid, the less internal pressure will be developed.

More Facts about Pneumatics  Universal Gas Laws - Pascal’s Law  Pressure acts at right angles to the confining vessel – That’s how a cylinder works

Transmission Principles

Valves are in Control  Control Pressure  Relief Valves & Regulators  Control Flow  Check Valves (used on compressor)  Flow Controls  Needle Valves

4-way 5-port Valves Directional Control SolenoidSpring

4-way Valves  Double Solenoid (detented)  SMC

4-way Valves  Single Solenoid (spring offset)  Festo FIRST Kickoff jrg

Valve Symbols  The 4-way valves included in the kit are actually pilot- operated valves.  Pilot-operators are 3-way nnp or nc (normally not passing or normally closed) valves built into the main valve.  This allows low-power solenoids to use the air pressure to switch the main spool. Solenoids that would actually move the main spool would be large, heavy and consume a lot of power.

FIRST Kickoff jrg Compressed Air is routed by the valve to extend or retract the cylinder Animations courtesy of Deyes High School pneumatic_systems.htm

Actuators Make things move Most Common types of Linear Actuators  Double Acting – Single Ended – Double Ended  Single Acting  Spring Return All contain Cylinder Barrel Piston Rod Seals Spring if used

Actuators Make things move Actuators available on order  Actuators can be ordered. One of those may be a rotary actuator. The order form and details are included in the KOP. These actuators can be ordered with reed position switches and magnetic pistons to indicate position. Note the inclusion of reed switches

Actuators Construction & Operation FIRST Kickoff jrg Basic Construction Operation

Actuators Operation with Flow Controls Operation Typically Flow Controls are mounted between the 4-way valve and the cylinder as close to the cylinder as practical. The check valve permits free flow into the cylinder from the valve and metered flow from the cylinder to exhaust

Actuators Differential Areas Force Consideration Consider the effective area on which the pressure acts On single ended cylinders there is a differential Don’t forget friction

Actuators Angles Power Factor Angle AFactor Force T = Cylinder Force x sin A

Actuators Angles

Actuators - Angles FIRST Kickoff jrg Example: Load 15 lbs Angle 50 Solution Step 1 – Force at right angles to support weight = 15 x.643 (cos 50 ) = 9.65 lbs = F2 Step 2 – Effective Cylinder Force at right angles to support weight = 9.65 x arm ratio (17/5) = lbs = F1 Step 3 – Actual Cylinder Force acting at 30 = F1 / sin 30 = lbs = F

Actuator (cylinder) Do’s and Don’ts  You do not have to fully extend a cylinder but you’ll need an external stop.  Avoid side-loading – increases friction and wear  Avoid getting grit or metal shavings on the rod or in the cylinder – causes abrasion, seal damage and leaks Weight or force applied at 90° angle to the rod Wear, friction and leakage can occur Wear, friction and leakage can occur at the rod seal and at the piston seal at the rod seal and at the piston seal

Actuator (cylinder) do’s and don’ts  Use flow controls for safety  Cylinder Force  Push Force =  x cylinder radius 2 x Pressure (psig)  Pull Force = Push Force -  x rod radius 2 x Pressure (psig)  Teams may order additional cylinders (including spares) for rapid delivery using the FAX form is on page 16 of the manual that is included in the kit. ¾”, 1-1/2” or 2” bore are available – see form for available strokes  Avoid leaks – reduces available energy

Actuators – Mounting Thoughts Example: Arm to be raised by Cylinder Determine overall length of retracted cylinder Draw an arc from the mounting point on arm Determine overall length of extended cylinder Draw an arc from the mounting point on arm Where arcs intersect is the mounting point Check for intermediate interference

Calculating Cylinder Dimensions Based on the drawings in the pneumatic manual included with the kit:  Retracted length from pivot pin to clevis hole =  Base Dimension +  Stroke Length +  Locking Nut +  Clevis Dimension  Extended length from pivot pin to clevis hole =  Retracted Length plus Stroke

1.5” Bore Cylinder Retracted Length = Stroke = Stroke Base Dimension = Stroke Length = ? + Locking Nut =.25 + Clevis Dimension = 1.31 Extended Length = (2 x Stroke Length)

Tips & Tricks  Minimize Leaks (better yet, remove them completely) by careful use of Teflon tape and careful assembly of tubing and fittings. Teflon tape should start two threads back and wrap in the direction of the threads.  With no movement taking place the compressor should charge the tanks and then shut off. It should not restart until a valve and cylinder is operated  Use the Compressor Vibration Isolators. The Compressor is a reciprocating device and will cause sympathetic vibrations throughout your assembly unless they are used.  When ordering custom cylinders, use extreme care on the form, both on the address and models ordered

Tips & Tricks  Pressure Switch must be used as inputs to the controller. They cannot handle the amperage of the compressor.  The Norgren Regulator should be first with the Monnier unit used after that if needed.  Make sure you have adequate pilot pressure (30 psi) for the valves.  When using the double solenoid valve, energize only coil one at time.  Fittings are not required in the exhaust ports unless the circuit requires them.  Always stay clear of cylinders in motion. Until compressed air is being metered, flow controls do little to control speed.  Download additional copies of the pneumatic manual from

Interesting Links Fluid Power Educational Foundation Nason Corporation Bosch Rexroth www. bosch- rexroth.com Bimba Manufacturing Lord Corp Fluid Power Dist. Ass’n Clippard Instrument Lab. Monnier, Inc. Fluid Power Society Wika e/GlobalSites.aspx Norgren Nat’l Fluid Power Ass’n Festo Parker SMC Pneumatics FIRST Kickoff jrg

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